Two sisters have sued a Staten Island cemetery and the New York Archdiocese for the unwelcome and unexplained moving of their third sister’s remains to the grave next door.

Juanita Scarfia was just 20 years old when she was given a military funeral and buried in St. Mary’s Cemetery in 1970, according to the Manhattan Supreme Court lawsuit.

Cemetery records show Scarfia was inexplicably dug up in 1989, the suit alleges. The vet’s body, but not her metal coffin, was puzzlingly reburied in an adjacent grave — that of a stranger who had also died in 1970, the suit alleges.

Nancy Roe of Manhattan and Santina Picataggio of Palm Beach Gardens, Fla., might never have known about the strange commingling if not for their attempt last year to move Scarfia’s remains to the family crypt in Moravian Cemetery on Staten Island — whereupon they were shocked to find her grave empty of corpse and casket.

When cemetery records pointed to the bordering grave, the sisters had that one opened as well, finding it filled with their sister’s “miscellaneous bones,” along with her wig, ID tag and military epaulets. The sisters are suing for an unspecified sum.

Cemetery officials did not immediately return calls requesting comment and the archdiocese has yet to see the lawsuit, a spokesman said.